In recent years, the rising cost of building materials and labor, in addition to the rising cost of energy and the resulting increased concern for energy efficiency, have prompted building designers to seek building materials which will provide greater energy efficiency at a lower construction cost than with conventional materials. With respect to materials used for constructing the exterior walls of residences and other buildings, a number of factors must be considered in evaluating the feasibility and usefulness of any proposed material, including structural integrity, weather resistance, insulation capabilities, sound transmission resistance, fire-proofing capabilities, ease and speed of construction, space requirements, ease of maintenance, and aesthetic appeal.
One of the oldest, most widely used and popular materials for constructing exterior walls is brick, a principal advantage of brick being the wide range of aesthetically pleasing colors and finishes which may be obtained using brick. In conventional exterior brick wall construction, a single layer or single "wythe" of brick is constructed by joining individual brick units with mortar with such single wythe wall having a thickness corresponding to the thickness of the individual brick units, a second backup interior wythe of brick or other suitable materials is constructed in close parallel relation thereto, and insulating material is placed between the two wythes. From a cost efficiency standpoint, this conventional operation is considerably more expensive than merely constructing a wall consisting of a single wythe of brick in that it is more time consuming and requires more labor and material. However, a single wythe wall of brick is not normally used without some form of backup wall because such a wall is inherently difficult to waterproof due to cracking of the mortar joints, because it has very little insulating value, and because the exterior surfaces of conventional brick are not normally aesthetically suitable for use both as an interior and exterior wall surface.
The aforesaid waterproofing problem associated with mortar joint brick walls is aggrevated by the inherent tendency of mortar joints to develop cracks, occuring as the result of a number of different factors. Thermal stresses caused both by daily and seasonal atmospheric temperature variations affecting the exterior wall surface and by temperature variations between the interior, room temperature and the exterior atmospheric temperature cause constant expansional and contractional movement in the wall. Building settlement, as well as a variety of other externally imposed forces, place additional stresses on the wall. All of these forces cause the conventional brick wall to shift or "squirm" slightly thereby causing hairline cracks in the mortar joints thereof. Typically, any such hairline crack will extend completely through the brick wall thereby providing a direct flow path for water and air entering the crack.
In contrast, the present invention provides a composite building unit usable in mortar joint wall construction in the same manner as conventional brick, a single wythe of which composite building unit will produce, at a cost significantly reduced in relation to the cost of comparable construction using conventional building materials, a well insulated, energy efficient, aesthetically appealing wall as structurally sound as conventional brick while providing improved waterproof characteristics as compared with a single wythe of conventional brick or other solid masory wall.